161. SUPERCONDUCTING MAGNETIC ENERGY STORAGE SYSTEM
Doomers say renewable energy is irrelevant to modern society because it is intermittent and unreliable. Modern 3MW wind turbines would be no good because when the wind doesn't blow then the lights go out.
Let me introduce SMES or Superconducting Magnetic Energy Storage. Not only is it 97% efficient but it can instantly discharge large quantities of power.
It stores energy in the magnetic field created by the flow of DC in a coil of superconducting material that has been cryogenically cooled. These systems have been in use for several years to improve industrial power quality and to provide a premium-quality service for individual customers vulnerable to voltage fluctuations. The SMES recharges within minutes and can repeat the charge/discharge sequence thousands of times without any degradation of the magnet. Recharge time can be accelerated to meet specific requirements, depending on system capacity.
... As an energy storage device, SMES is a relatively simple concept. It stores electric energy in the magnetic field generated by DC current flowing through a coiled wire. If the coil were wound using a conventional wire such as copper, the magnetic energy would be dissipated as heat due to the wire's resistance to the flow of current. However, if the wire is superconducting (no resistance), then energy can be stored in a "persistent" mode, virtually indefinitely, until required. Superconductors have zero resistance to DC electrical current at low temperatures so that ohmic heat dissipation is eliminated, hence the refrigerator is needed in the SMES to cool the coil. In AC applications, there are still electrical losses, but these can be minimised through appropriate wire architecture and device design. For both DC and AC applications, energy savings will be significant.Source
An SMES system includes a superconducting coil, a power conditioning system, a cryogenically cooled refrigerator and a cryostat/vacuum vessel. SMES are highly efficient at storing electricity (greater than 97% efficiency), and provide both real and reactive power. These facilities are used to provide grid stability in a distribution system and power quality at manufacturing plants requiring ultra-clean power, such as microchip fabrication facilities.
Energy is stored directly in a superconducting magnetic energy storage system. It is able to store energy with a loss of only 0.1% per hour (this is required for the cooling system), compared to a loss of about 1% per hour loss for flywheels. It is claimed that SMES is 97-98% efficient and it is much better at providing reactive power on demand. So far, SMES have only operated on a relatively small scale. However, projects have been started with SMES on a much commercially larger scale. This is very beneficial, as the unit cost of SMES facilities will decrease as the size increases.At this point SMES systems are able to store up to about 10 MW. Some research groups have achieved much higher capacities of hundreds of MW, but only for a second. However, some researchers believe SMES can potentially store up to 2000 MW. Theoretically, a coil of around 150-500 m radius would be able to support a load of 5000 MWh, at 1000 MW; depending on the peak field and ratio of the coil's height and diameter.Recent developments have tried to use silicone-based three-phase adjustable speed motor drives (ASDs), which bring down the scale of SMES to fit into lorry trailers. Storing energy in the range of 1-10 MWs, they are aimed at the power quality market.
-- by Wildwell